The long-term objectives of our research program are to understand the mechanisms which produce ovulation in mammals. We recently developed a new in vivo injection technique for topically applying drugs to hamster ovaries. Using this technique and electron microscopy, we demonstrated that smooth muscle cells (SMC) at the base of hamster follicles contract minutes prior to ovulation and that inhibition of this contraction also inhibits ovulation. We now propose to use this new technique to determine if proteinases are involved in weakening the apex of preovulatory hamster follicles. Specific serine, thiol, carboxyl and metallo endopeptidase inhibitors will be injected into the bursal cavities of hormone primed females 4 hrs before predicted ovulation and their affect on ovulation will be assessed 6 hrs later; one bursal cavity receives an injection of normal saline only serves as the control. Results will establish which classes of endopeptidases participate in ovulation and more specifically will determine if inhibitors of trypsin, plasmin, cathepsin D, elastase, or collagenase block hamster ovulation. We then propose to treat ovaries with effective inhibitors and determine what degradative events are blocked. Control (untreated) and experimental (exposed to an inhibitor) ovaries will be compared by electron microscopy at 2 and 0.5 hrs before ovulation. Results will establish if particular inhibitors prevent: (1) degradation of basement membranes, cell junctions, collagen or elastin; or (2) release of the cumulus mass or granulosa cells from the follicle wall. Finally, we propose to locate histochemically specific proteinases in hamster follicles using 4-methoxy-2-naphthylamine derivatives as substrates. These histochemical techniques will establish which regions (apex, lateral or base) and which cell layers of th preovulatory follicle contain specific proteinases. The overall study should establish: (1) if proteinases are required for ovulation; (2) the role of particular proteinases in rupture of the apex; and (3) the location of specific proteinases in the preovuiatory follicle. This knowledge will contribute to our general understanding of mammalian ovulation and may bring us closer to satisfactory methods for its regulation.